Categorizing species according to their functional traits, such as spatial and temporal patterns of resource use, effects on ecosystems, and responses to environmental perturbations, can facilitate successful restoration of plant communities. Functional guilds condense species lists by grouping species according to similarities in characteristics we believe to be important in a particular context. These groupings can allow us to (1) ensure community and ecosystem structural and functional attributes, (2) increase competitiveness of the community to deter the establishment of undesirable species, (3) simplify and test models of community assembly including resistance to invasion, succession, and species coexistence, and (4) facilitate cross-site comparisons. As useful as functional guilds can be, we must not overlook the potentially important roles of individual species. In restoration, including multiple species that represent each functional type within a target community may provide a buffer against environmental change. Functional guilds provide realistic conceptual units to ensure that restored plant communities include species that confer the ecological functions of most importance the majority of the time.

Additional index words: Community assembly, competition, functional traits, invasion, resource use, stability.

Abbreviations: CCNHA, Cedar Creek Natural History Area; CO₂, carbon dioxide; N, nitrogen; NO₃, nitrate.